As illustrated in FIG. 8 and FIG. 9, a steering apparatus for an automobile is constructed, for example, so that rotation of a steering wheel 1 is transmitted to an input shaft 3 of a steering-gear unit 2, and as the input shaft 3 rotates, a pair of left and right tie rods 4 are pushed and pulled so as to apply a steering angle to the front wheels (steered wheels). The steering wheel 1 is supported by and fastened to the rear-end section of a steering shaft 5, and with this steering shaft 5 inserted into a cylindrical shaped steering column 6, the steering shaft 5 is supported by the steering column 6 so as to be able to rotate freely. Moreover, the front-end section of the steering shaft 5 is connected to the rear-end section of an intermediate shaft 8 by way of a universal joint 7, and the front-end section of this intermediate shaft 8 is connected to the input shaft 3 by way of a separate universal joint 9.
The steering apparatus for an automobile that is illustrated in the figures, together with comprising an electric power steering apparatus 10 that assists the operator steer by way of rotation of a motor, also comprises a tilt mechanism for adjusting the up-down position of the steering wheel, and a telescopic mechanism for adjusting the forward-backward position of the steering wheel 1. Therefore, the front-end section of the steering column 6 fits with and fastens to the rear-end section of a housing 11 that houses the component parts of the electric power steering apparatus 10, and this housing 11 is supported by the vehicle body 12 so as to be able to pivot around a horizontal shaft 13 that is arranged in the left-right direction. The steering shaft 5 comprises a combination of an inner shaft 15 and an outer shaft 16 that are capable of transmitting rotation force and are capable of relative displacement in the axial direction. On the other hand, the steering column 6 comprises a combination of an inner column 17 and an outer column 18 that are capable of relative displacement in the axial direction. Furthermore, the portion near the rear end of the outer column 18 is supported by a vehicle-side bracket 19 that is supported by the vehicle body 19 so that the fastened state to the vehicle side bracket 19 can be switched between a fastened state and unfastened state.
In order to achieve this kind of support construction, a pair of holding plate sections 20 of the vehicle-side bracket 19 are arranged at a position on both sides in the left-right direction of the portion near the rear end of the outer column 18 and a column-side bracket 21 that is attached and fastened to the bottom surface of this portion near the rear end. Arc-shaped long holes 22 in the up-down direction that center around the horizontal shaft 13 are formed at positions in these holding plate sections 20 so as to be aligned with each other. Moreover, long holes 23 that are long in the forward-backward direction in the axial direction of the outer column 18 are formed at positions in the side plate sections of the column-side bracket 21 so as to be aligned with each other. An adjustment rod 24, which is a rod shaped member, is inserted in the forward-backward long holes 23 and the up-down long holes 22. A head section 25, which is a pressing section, is formed on the base-end section of this adjustment rod 24. An adjustment nut 26, which is a pressing section, is screwed onto the portion of the tip end section of this adjustment rod 24 that protrudes from the up-down hole 22, and the base-end section of an adjustment lever 27 is connected and fastened to this adjustment nut 26. In the construction illustrated in the figure, the adjustment rod 24, the adjustment nut 26 and the adjustment lever 27 form an expanding-contracting mechanism for switching between the fastened state and unfastened state between the vehicle-side bracket 19 and the steering column 6.
When adjusting the up-down position and the forward-backward direction of the steering wheel 1, the adjustment lever 27 is operated, and by loosening the adjustment nut 26 the distance between the inside surfaces of the holding plate sections 20 is expanded. As a result, the friction force that acts between the holding plate sections 20 and the side plate sections of the column-side bracket 21 is sufficiently decreased, and the fastened state of the outer column 18 to the vehicle-side bracket 19 is released. In this state, when the up-down position of the steering wheel 1 is adjusted, the steering column 6 and steering wheel 1 are pivoted around the horizontal shaft 13 within a range that the adjustment rod 24 can displace inside long hole 22 in the up-down direction. On the other hand, when the forward-backward position of the steering wheel 1 is adjusted, the entire length of the steering column 6 and steering shaft 5 is extended or contracted within the range the adjustment rod 24 can displace inside the long hole 23 in the forward-backward direction. After adjustment, the adjustment lever 27 is operated, and the adjustment nut 26 is tightened. By doing so, the friction force is sufficiently increased, and the outer column 18 is fastened to the vehicle-side bracket 19. As a result, the steering wheel 1 is held in the adjusted position.
Incidentally, as construction for connecting the front-end section of the steering column 6 and the rear-end section of the housing 11 of this kind of steering apparatus, construction in which the front-end section and the rear-end section fit together in the axial direction is widely used. As an example of this kind of connecting construction, JP2011-46309(A) discloses construction in which the cylindrical shaped front-end section of the steering column is pressed onto and fits around a cylindrical shaped section that is formed on the rear end section of the housing with an interference fit. Moreover, JP2000-85596(A) discloses a method in which the front end section of a steering column having a notched cylindrical shape fits around a cylindrical section that is formed on the rear-end section of the housing, then a fastener fits around this front end section and by elastically constricting the diameter of the front-end section with this fastener, the inner surface of the front-end section forms a strong friction fit with the outer circumferential surface of the cylindrical section. Furthermore, JP2008-87583(A) discloses construction in which the cylindrical shaped front-end section of the steering column fits inside a circular hold that is formed on the rear-end section of the housing, and a flange section that is formed around the outer circumferential surface of the portion near the front end of the steering column is connected and fastened to the rear-end surface of the housing with a plurality of bolts.
When using any of the conventional construction as construction for connecting the front-end section of the steering column 6 and the rear-end section of the housing 11, the assembled direction of the steering column 6 with respect to the housing 11 when assembling this connection is in the axial direction of the steering column 6. On the other hand, when assembling the portion near the rear end of the steering column 6 in the vehicle-side bracket 19, this portion near the rear end of the steering column 6 is inserted between the holding plate sections 20 of the vehicle-side bracket 19 from the bottom edge side of these holding plate sections 20. In other words, the assembly direction of the steering column 6 in the vehicle-side bracket 19 is in the radial direction of the steering column 6. In this way, in the case of the conventional construction, the assembly direction of the steering column 6 in the housing 11 and the assembly direction of the steering column 6 in the vehicle-side bracket 19 are different.